Digital picture producing apparatus on photographic basis, so-called digital photographic printers, produce paper copies or copies by projecting the image information of the underlying original present in an electronically stored format onto photographic copy material. For example, the image information of the original can be picture by picture optically reproduced for each image by way of a digitally operable mirror matrix. Accordingly, an optical representation of the original can be produced and this optical representation of the original projected onto the copy material and thereby exposed thereonto.
With line by line or strip-wise projection using the micro mirrors of the mirror matrix any size photographic pictures can be theoretically produced in the direction transverse to the lines or strips. Respectively strip shaped portions of the original which in the longitudinal direction cover the whole original can be optically produced one behind the other by way of the mirror matrix and sequentially exposed in corresponding spatial orientation onto the copy material. The correct spatial positioning of the exposed strips is thereby achieved by displacement of the copy material relative to the exposure light path. This can be achieved by advancement of the copy material or by correspondingly movable projection optics. The relative displacement takes place synchronously with the change of the reproduced strips of the original. If the strips are several lines wide, adjacent strips can possibly also overlap. If the copy material depending on the degree of overlap is in some regions multiply exposed, this must be correspondingly taken into consideration for the adjustment of the amount of copier light used in the individual exposure steps. This exposure process is known under the acronym TIG (Time Integration Gray Scale).
Relatively satisfactory photographic prints can be produced with the above described methods and the use of a conventional micro mirror matrix. The manufacturing costs for such arrangements for the manufacturing of a photographic picture are relatively high and the speed with which these photographic pictures can be produced is often less than desirable, especially when the light intensity per surface area is small during the exposure so that long exposure times are required.